21726321 has 8 divisors (see below), whose sum is σ = 29050560. Its totient is φ = 14443152.

The previous prime is 21726317. The next prime is 21726349. The reversal of 21726321 is 12362712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21726321 - 2² = 21726317 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21726291 and 21726300.

It is not an unprimeable number, because it can be changed into a prime (21726311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9010 + ... + 11163.

It is an arithmetic number, because the mean of its divisors is an integer number (3631320).

Almost surely, 2^21726321 is an apocalyptic number.

It is an amenable number.

21726321 is a deficient number, since it is larger than the sum of its proper divisors (7324239).

21726321 is a wasteful number, since it uses less digits than its factorization.

21726321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20535.

The product of its digits is 1008, while the sum is 24.

The square root of 21726321 is about 4661.1501799449. The cubic root of 21726321 is about 279.0371733976.

The spelling of 21726321 in words is "twenty-one million, seven hundred twenty-six thousand, three hundred twenty-one".